如何使用BLE OBDII外设 [英] How to use BLE OBDII Peripheral

问题描述

我正在尝试创建一个iOS应用，该应用将从OBDII蓝牙4(LE)设备读取.我购买了Vgate icar3蓝牙(4.0)elm327 OBDII.我将其插入我的车中，然后找到宣传一些服务的IOS-VLink外设.然后，我可以获得这些服务的特征.这些是我发现的服务:

I'm trying to create an iOS app that will read from an OBDII Bluetooth 4 (LE) device. I purchased a Vgate icar3 bluetooth(4.0) elm327 OBDII. I plug it into my car and find IOS-VLink peripheral that advertises some services. I can then get the characteristics for those services. These are the services I find:

<CBService: 0x1780729c0, isPrimary = YES, UUID = Battery>
<CBService: 0x178072a80, isPrimary = YES, UUID = 1803>
<CBService: 0x178072ac0, isPrimary = YES, UUID = 1802>
<CBService: 0x178072b00, isPrimary = YES, UUID = 1811>
<CBService: 0x178072b40, isPrimary = YES, UUID = 1804>
<CBService: 0x178072b80, isPrimary = YES, UUID = 18F0>
<CBService: 0x178072bc0, isPrimary = YES, UUID = Device Information>
<CBService: 0x178072c00, isPrimary = YES, UUID = E7810A71-73AE-499D-8C15-FAA9AEF0C3F2>

但是我不知道1803、1802、1811、1804和18F0服务是什么或如何使用它们.这是我的简单程序，可以找出正在宣传的内容.

But I have no idea what the 1803, 1802, 1811, 1804 and 18F0 services are or how to use them. Here is my simple program to find out what is being advertised.

class ViewController: UIViewController, CBCentralManagerDelegate, CBPeripheralDelegate {

var centralManager = CBCentralManager()
var peripherals = [CBPeripheral]()
@IBOutlet weak var outputTextView: UITextView!

override func viewDidLoad() {
    super.viewDidLoad()
    centralManager.delegate = self
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
}

func centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral) {
    print("connected to \(peripheral.name ?? "unnamed")")
    peripheral.delegate = self
    peripheral.discoverServices(nil)
}

func centralManagerDidUpdateState(_ central: CBCentralManager) {
    if central.state == .poweredOn {
        central.scanForPeripherals(withServices: nil, options: nil)
    }
}

func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) {
    if peripheral.name == "IOS-Vlink" {
        peripherals.append(peripheral)
        print(peripheral.name ?? "peripheral has no name")
        print(peripheral.description)
        central.connect(peripheral, options: nil)
        central.stopScan()
    }

}

func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?) {
    guard let services = peripheral.services else {
        return
    }
    for service in services {
        print(service.description)
        peripheral.discoverCharacteristics(nil, for: service)
    }
}

func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) {
    guard let chars = service.characteristics else {
        return
    }
    for char in chars {
        print(char.description)
    }
}
}

推荐答案

我知道了. "E7810A71-73AE-499D-8C15-FAA9AEF0C3F2"服务具有uuid为"BEF8D6C9-9C21-4C9E-B632-BD58C1009F9F"的特征.如果将AT命令写入该特征，则它将调用peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?)，然后在value属性中获取结果.这是发送简单ATZ命令的代码.此时，它只是使用了正确的OBDII ELM327命令.

I figured it out. The "E7810A71-73AE-499D-8C15-FAA9AEF0C3F2" service has a characteristic with a uuid of "BEF8D6C9-9C21-4C9E-B632-BD58C1009F9F". If you write an AT command to that characteristic then it calls peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) and then get the results in the value property. Here is the code sending a simple ATZ command. At this point it is simply using the correct OBDII ELM327 commands.

class ViewController: UIViewController, CBCentralManagerDelegate, CBPeripheralDelegate {

var centralManager = CBCentralManager()
var peripherals = [CBPeripheral]()
@IBOutlet weak var outputTextView: UITextView!

override func viewDidLoad() {
    super.viewDidLoad()
    centralManager.delegate = self
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
}

func centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral) {
    print("connected to \(peripheral.name ?? "unnamed")")
    peripheral.delegate = self
    peripheral.discoverServices([CBUUID(string:"E7810A71-73AE-499D-8C15-FAA9AEF0C3F2")])
}

func centralManagerDidUpdateState(_ central: CBCentralManager) {
    if central.state == .poweredOn {
        central.scanForPeripherals(withServices: nil, options: nil)
    }
}

func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) {
    if peripheral.name == "IOS-Vlink" {
        peripherals.append(peripheral)
        print(peripheral.name ?? "peripheral has no name")
        print(peripheral.description)
        central.connect(peripheral, options: nil)
        central.stopScan()
    }

}

func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?) {
    guard let services = peripheral.services else {
        return
    }
    for service in services {
        peripheral.discoverCharacteristics([CBUUID(string:"BEF8D6C9-9C21-4C9E-B632-BD58C1009F9F")], for: service)
    }
}

func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) {
    guard let chars = service.characteristics else {
        return
    }
    guard chars.count > 0 else {
        return
    }
    let char = chars[0]
    peripheral.setNotifyValue(true, for: char)
    peripheral.discoverDescriptors(for: char)

    print (char.properties)
    peripheral.writeValue("ATZ\r\n".data(using: .utf8)!, for: char, type: CBCharacteristicWriteType.withResponse)

    peripheral.readValue(for: char)
    if let value = char.value {
        print(String(data:value, encoding:.utf8) ?? "bad utf8 data")
    }
}

func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?) {
    if let value = characteristic.value {
        print(String(data:value, encoding:.utf8)!)
    }
}
func peripheral(_ peripheral: CBPeripheral, didDiscoverDescriptorsFor characteristic: CBCharacteristic, error: Error?) {
    print(characteristic.descriptors ?? "bad didDiscoverDescriptorsFor")
}
func peripheral(_ peripheral: CBPeripheral, didWriteValueFor characteristic: CBCharacteristic, error: Error?) {
    if let error = error {
        print(error)
    }
    print("wrote to \(characteristic)")
    if let value = characteristic.value {
        print(String(data:value, encoding:.utf8)!)
    }
}
}

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